Wiring for telephone and data networks should be installed
using standardized wiring schemes that are developed and maintained
by the Electronic Industries Alliance and the Telecommunications
Industry Association (EIA/TIA). Following the wiring guidelines
contained in these codified standards will ensure that wire and cabling
systems work properly with all standardized equipment and will aide in
the future testing and repair of these systems.
The basic (and out dated) wire used to connect telephones is
called station wire (aka "quad or JK") and is suitable only for standard
voice telephone systems. It is made of four conductors that are not twisted
pairs inside a protective jacket. The standard colors for these conductors
is red, green, yellow, and black. This type cable is not commonly used today,
it is included because you will frequently encounter it in older buildings.
You can test for proper polarity with a test meter by placing the positive (usually red) lead on the Tip terminal (green or black wire) and the negative (usually black) lead on the Ring terminal (red or yellow wire) at any convenient junction box. The test meter should read a positive 48 volts DC if all phones are hung up or disconnected and about 10 volts DC if a phone is off hook during the test. WARNING!-When the phone rings their is 90 volts AC present on the line, and it can really give you a jolt, so be careful.
Category WiringToday every phone circuit is a potential data connection for such things as internet access and data transfer by modem. New and improved wire has been developed to handle the higher demands placed on it by such devices.
The wire used today for voice and data networks is called "Category" (CAT) wire. Cable categories are determined by its performance characteristics with lower Cat numbers such as Cat 3 having lower performance and higher Cat numbers higher performance. Cat 3 wire is currently used for voice and limited data transfer using a modem. Cat 5 is the industry standard for local area networks (LAN) that connect computers in most businesses.
This new wire uses a different and somewhat more complicated color scheme than station wire and is based on a primary color and a secondary color. The primary colors are white, red, black, yellow, violet, and the secondary colors are blue, orange, green, brown, slate. In this newer scheme; the "tip" wire is the primary color with marks of the secondary color (i.e., white with blue marks) and the "ring" wire is the secondary color, with marks of the primary color (i.e., blue with white marks).
Wire pairs are marked in groups of five. Each pair within a group uses the same primary color and a different secondary color; each group uses a different primary color. This allows identification of up to 25 pairs without duplication. This is likely to be the largest cable you will ever encounter in most residential or business environments.
Cat 5 wire cables with four pairs are used extensively for most residential and office installations today. This cable has 8 conductors that are twisted into 4 pairs, it comes with and without a shield and is commonly referred to as Unshielded or Shielded Twisted Pair (UTP & STP for short) cable. The four pairs are colored blue, orange, green, and brown for pairs 1 through 4 respectively. This wire is used for multi-line telephone and ethernet LAN applications in both residential and business premises.
Wiring Modular Plugs and JacksWhen using Cat 5 wire for data applications virtually all connections are made with modular plugs and jacks. This modular equipment is made for a multitude of different applications and they all are physically similar; however, their internal wiring is specific to each application. The following charts and diagrams should help to visualize the various wiring methods.
Category 5 wiring standards:
EIA/TIA 568A/568B and AT&T 258A define the wiring standards and define two different wiring color codes.
Modular jacks have internal pigtail leads that connect to their contacts. This diagram shows the most common wiring color scheme used for these devices.
The Ubiquitous RJ31X Jack
The Federal Communications Commission regulations state that
every electronic device that attaches to the telephone network is required
to have a Registered Jack (RJ) as the means of connection. The RJ allows
the device to be disconnected quickly from the telephone circuit if a problem
develops on the line.